Control-rope for dumb-waiters.



UNITED STATES PATENT onnron.

GUY K. MITCHELL, 0F BALTIMORE, MARYLAND.

CONTROL-ROPE FOR DUMB-WAITERS.

Specification of Letters Patent. Patented Sept. 24, 1918.

Application filed August 9, 1917. Serial No. 185,260.

To all whom it may concern:

Be it known that I, GUY K. MITCHELL, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Control-Ropes for Dumb-Waiters, of which the following is a specification.

This invention relates to dumb Waiters, and more particularly to an improved construction of hand rope therefor.

As usually constructed, dumb waiters comprise a hoisting drum having an operating wheel around which passes a hand rope which extends the full length of the shaft and carries at its lower end a floating tail sheave. This tail-sheave is usually mounted in bearings which permit of free vertical movement, and the Weight of the sheave serves to take up the slack in the hand rope and cause it to operate smoothly.

As heretofore constructed, great difficulty has been experienced with dumb waiters of this type on account of the changes in the length of the hand rope produced by atmospheric conditions, and also by wear. The possible amount of vertical movement of. the tail-sheave must necessarily be limited and it has been found that where a hand rope is cut to the properlength, when new, and its ends spliced, such rope elongates from use and eventually becomes so slack that the tail sheave reaches the lower limit of its movement and thereupon becomes inoperative to maintain the hand rope taut. This is especially true if, at the time the apparatus is installed, the atmosphere happens to be damp. hen conditions change, and the rope dries out, it lengthens so much asto cause trouble.

If, on the other hand, the rope should be out to proper length when dry and should then, through atmospheric conditions, become wet, it will shrink and shorten to such an extent as to move the tail-sheave to the upper limit of its travel, and then cause an objectionable tightness.

It is the primary object of the present invention, therefore, to provide practical means for adjusting the length of these hand ropes in accordance with working conditions caused by atmospheric changes or wear. To this end, I contemplate the employment of a' separable coupling, the parts of which or shortening of the rope by means of twist- 111g such ends.

In installations where tail-sheaves have not been employed, trouble has been experienced on account of the tendency of the free loop of the hand rope to curl up and become tangled, due to the inherent twist of the strands. A further object of the present invention is therefore to provide a coupling which will permit of the twist being taken out of such a rope to an extent suflicient to prevent it from curling.

In order that the invention may be clearly understood, reference is had to the accompanying drawings, forming a part of this specification, and in which,

Figure 1 is a front view of a dumb waiter as usually installed, showing my improved coupling applied thereto;

Figs. 2 and 3 are views of the coupling itself on an enlarged scale, the views being taken on planes 90 degrees apart; and,

Fig. 4C is a View similar to Figs. 2 and 3, showing how my improved coupling adapts itself to the curve of the wheel.

Referring to the drawings in detail, A represents a dumb waiter car which is supported by means of the cable B, passing over a drum C, supported on suitable framework. To the drum C is secured a hand wheel D, around which passes the hand rope E, having its ends connected by means of my improved coupling F. At the bottom of the shaft, the hand rope passes around a tailsheave G, secured to a frame H, which is free to slide upon guides J, within certain limits, These limits are represented by a crossbar K at the top, and the base or ground X at the bottom.

Referring to Figs. 2, 3, and 4., it will be seen that my improved coupling consists of two members a and b. The member a comprises a closed loop 1, through which the strands of the rope are threaded, and a hook 2. The member 6 comprises a similar loop 4L, through which the strands of the other rope end are threaded, and an eye 5. This eye has a front portion 6, of relatively great thickness, and relatively thin side portions 7. It will be seen from the drawings that the portion 6 is too large to pass through the opening 3 of the hook 2, and that in order to connect or disconnect the coupling, the members a and 6 must be swung at right angles to each other so as to bring the thin part 7 of the eye adjacent the opening 3 in the hook. When this is done, the parts may be readily uncoupled. The part 6 oi the eye is preferably rounded on the inside so as to turn freely about the hook and thus permit the coupling to bend and pass easily around the wheels, as shown in Fig. 4. Owing to the relative sizes of the portion 6 and opening 3, it is impossible for the members of the coupling to become disconnected so long as the rope ends remain in alinement.

It will be understood that the preferred method of attaching the rope ends to the coupling members is to partially unravel the strands of the rope and pass them through the loops 1 and t, whereupon the loose ends of the strands are woven in between the twisted strands, as indicated at E. It will be seen that the result of this method of attaching the coupling members is that they are nonrotatably secured to the rope ends so that a twist imparted to the rope ends before being coupled is held or maintained after the coupling has been joined.

In practice, the rope is cut to approximately the proper length and the coupling members permanently secured thereto, prefably by the method described. Then, when the rope is applied to the machine, the ends are connected by means of the coupling. Should the rope become too long, the coupling is disconnected and the ends of the rope twisted up. This tends to shorten the rope and the coupling is then connected again, thus maintaining the adjustment produced. If, on the other hand, the rope becomes too short, the coupling is disconnected and the ends untwisted, thereby permitting the rope to lengthen. In this way, it will be seen that it is possible to adjust the tension of the rope at any time and to maintain it at such a length that the movement of the tail-sheave between its upper and lower stops or limits is sufiieient to take care of normal variations in the rope caused by atmospheric. changes.

My improved coupling is also advantageous in installations where no tail-sheave is employed. In such-installations, trouble is often experienced owing to the tendency of the lower loop of the rope to curl up and become tangled, due to the inherent twist of the strands. When a hand rope equipped with my improved coupling shows this tendency to curl, it is simply necessary to disconnect the coupling and untwist the rope until it hangs straight and free.

Therefore, whether hand ropes are used with or without; tail-sheaves, my improved detachable coupling furnishes ready means by which the rope may be twisted or untwisted as may be necessary to secure proper working.

WVhat I claim is:

1. The combination with a dumb waiter having the usual. hand wheel, of a hand rope formed of twisted strands passing around said. wheel, and a detachable coupling uniting the ends of said rope, said coupling comprising a pair of members non-rotatably secured to the rope ends, whereby said rope may be lengthened or shortened by disengaging said coupling members twisting the rope ends in opposite directions, and reengaging said members.

2. The combination with a dumb waiter having the usual hand wheel and tail-sheave guides on which said sheave is vertically movable, and means for limiting such movement, of a hand rope passing around said wheel and sheave, and a detachable coupling in said hand rope, such coupling con1prising a pair of'members each having a loop through which the strands of the hand rope are threaded, one of said members comprising a hook and the other having an eye with which said hook is engaged.

In testimony whereof I have atlixed my signature.

' GUY K. MITCHELL.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner 0! latents,

Wuhington, D. 0." 

